chemistry

• What is a compound?

  A compound is a substance that contains two or more different types of atoms chemically bonded together
• How many hydrogen atoms are in one molecule of water?

  There are two hydrogen atoms in one molecule of water
• What happens to atoms during a chemical reaction?

  Atoms change what they're bonded to and how they're bonded through chemical reactions
• Why must chemical equations be balanced?

  Because atoms are not created or destroyed in a chemical reaction, the same number of each type of atom must be on both sides
• What is the first step in balancing a chemical equation?

  Start balancing atoms that are only in compounds
• How do you balance hydrogen atoms in a reaction?

  By placing a coefficient in front of the compound containing hydrogen
• What is a mixture?

  A mixture is any combination of different types of elements and compounds that aren't chemically bonded together
• Give an example of a mixture.

  Air, which is a mixture of oxygen, nitrogen, and more
• How can you separate large insoluble particles from a liquid?

  By using filtration
• What is crystallization used for?

  To separate a solute from a solvent after evaporating the solvent
• What is the process of distillation?

  Heating a solution to separate components based on their boiling points
• What is fractional distillation?

  Separating different liquids in a mixture based on their different boiling points
• What are the three main states of matter?

  Solid, liquid, and gas
• How do particles behave in a solid state?

  Particles vibrate around fixed positions
• What happens to particles when a substance melts or evaporates?

  Energy is supplied to overcome the electrostatic forces of attraction between the particles
• What do state symbols indicate in chemical equations?

  They indicate the state of substances: (s) for solid, (l) for liquid, (g) for gas, and (aq) for aqueous
• Who proposed the plum pudding model of the atom?

  JJ Thompson
• What did Ernest Rutherford discover about the atom?

  He discovered that the positive charge is concentrated in a small nucleus
• What are neutrons and protons?

  Neutrons are neutral particles, and protons are positively charged particles in the nucleus
• What is the atomic number of an element?

  The atomic number is the number of protons in the nucleus
• What happens when an atom gains or loses electrons?

  It becomes an ion
• What is the mass number of an atom?

  The mass number is the total number of protons and neutrons in the nucleus
• What are isotopes?

  Isotopes are atoms of the same element with different numbers of neutrons
• How is the average relative atomic mass calculated?

  By considering the relative abundance of each isotope
• What did Dmitri Mendeleev contribute to the periodic table?

  He grouped elements based on their properties, even if the order didn't follow atomic weight
• How do electrons fill the shells around the nucleus?

  Electrons fill shells from the inside out, with a maximum of 2 in the first shell and 8 in the second and third shells
• What are the properties of metals?

  Metals donate electrons to achieve a full outer shell and are typically good conductors of electricity and heat
• What are the properties of nonmetals?

  Nonmetals accept electrons to achieve a full outer shell
• What are alkali metals?

  Group 1 metals that have one electron in their outer shell and readily donate it
• How does reactivity change in alkali metals as you go down the group?

  Reactivity increases as you go down the group
• What are halogens?

  Group 7 elements that have seven electrons in their outer shell and need one more to achieve a full shell
• How does reactivity change in halogens as you go down the group?

  Reactivity decreases as you go down the group
• What are noble gases?

  Group 0 elements that have a full outer shell and are very unreactive
• What happens to metals when they lose electrons?

  They become positively charged ions
• What charge do group 1 metal ions have?

  Group 1 metal ions have a charge of +1
• What charge do group 2 metal ions have?

  Group 2 metal ions have a charge of +2
• What charge do group 7 nonmetal ions have?

  Group 7 nonmetal ions have a charge of -1
• What is the charge of aluminum ions?

  Aluminum ions have a charge of +3
• How do transition metals behave in terms of electron donation?

  Transition metals can donate different numbers of electrons
• What is metallic bonding?

  Metallic bonding involves a lattice of positive ions surrounded by delocalized electrons